1. Field of the Invention
The present invention relates to a structure of an ink-jet printer head such as those based on the piezoelectric system.
2. Description of the Related Art
A piezoelectric ink-jet printer head of the on-demand type concerning the conventional technique is described in Japanese Patent Application Laid-open No. 2001-246744, corresponding to U.S. Patent Application Publication No. U.S. 2001/0020968 A1. This patent document discloses the construction of a cavity unit obtained by stacking a nozzle plate which includes a plurality of nozzles arranged in an array form, a base plate which includes pressure chambers each disposed for each of the nozzles and arranged in an array form in the direction of the array of the nozzles, a manifold plate which is provided with a manifold chamber to serve as a common ink chamber for supplementing the ink to the respective pressure chambers after storing the ink supplied from an ink supply source, and a spacer plate which is interposed between the manifold plate and the base plate. In this arrangement, ink supply flow passages, which make the communication from the respective pressure chambers to the corresponding nozzles, are formed to make the penetration through the manifold plate and the spacer plate. Further, ink flow passages, which make the communication from the manifold chamber to the respective pressure chambers, are formed for the spacer plate. The disclosed structure includes a piezoelectric actuator which is stacked on the upper surface of the base plate and which has activating sections capable of being selectively driven for each of the pressure chambers to jet the ink.
In the cavity unit constructed as described above, a predetermined number of nozzles are formed at predetermined spacing distances to penetrate through the plate thickness of the thin metal plate (plate). The ink supply flow passages and the ink flow passages are formed for the other plates (manifold plate and spacer plate) as well. The manifold plate has the manifold chamber which occupies a large range, which makes it possible to supply the ink to all of the pressure chambers, and which is formed to make the penetration through the plate thickness as well. The following problem arises because the plates as described above are stacked.
That is, it is necessary that the respective plates are previously bored, for example, with the predetermined numbers of the nozzles, the pressure chambers, and the ink flow passages for making the communication therebetween at the predetermined spacing distances. When a product, which has an increased or decreased number of nozzles (pressure chambers), is produced, it is necessary to manufacture the product by determining the size of the plates from the beginning corresponding thereto. Therefore, it has been impossible to adopt manufacturing steps capable of immediately responding to any arbitrary change of the number of nozzles (number of pressure chambers).
In the conventional technique, the plurality of plates as described above are stacked and joined. Therefore, the following problem has arisen. That is, any stacking deviation tends to occur during the operation. In particular, it is difficult to make the smooth communication of the ink supply flow passages having small diameters over the range from the pressure chambers to the nozzles.